Despite being the most available natural polymer on earth, it is only recently that cellulose has gained prominence as a nanostructured material, in the form of nanocrystalline cellulose (NCC), nanofibrillar cellulose (NFC), and bacterial cellulose (BC). Nanocellulose is being developed for use in a wide variety of applications such as polymer reinforcement, antimicrobial films, biodegradable food packaging, printing papers, pigments and inks, paper and board packaging, barrier films, adhesives, biocomposites, wound healing, pharmaceuticals and drug delivery, textiles, water-soluble polymers, construction materials, recyclable interior and structural components for the transportation industry, rheology modifiers, low-calorie food additives, cosmetics thickeners, pharmaceutical tablet binders, bioactive paper, pickering stabilizers for emulsion and particle stabilized foams, paint formulations, films for optical switching, and detergents.
Improved processes for producing nanocellulose from biomass at reduced energy costs are needed in the art. Also, improved starting materials (i.e., recycled pulp and paper products) are needed in the art for producing nanocellulose. It would be particularly desirable for new processes to possess feedstock flexibility and process flexibility to produce either or both nanofibrils and nanocrystals, as well as to co-produce sugars, lignin, and other co-products. For some applications, it is desirable to produce nanocellulose with high crystallinity, leading to good mechanical properties of the nanocellulose or composites containing the nanocellulose. For certain applications, it would be beneficial to increase the hydrophobicity of the nanocellulose.
Post-use corrugated packaging material is commonly known as “cardboard,” while it is typically referred to as old corrugated containers (OCC) in the industry. Corrugated cardboard can easily be recognized by its multiple-layer structure; the fluted or wavy middle layer between sheets of paper keeps corrugated board light and gives it the strength to carry products. OCC fiber is a high-volume, low-cost recycled feedstock. OCC is mainly composed of cellulose, with relatively low content of hemicellulose, lignin, and impurities. Currently, OCC is mainly used to cost-effectively produce new paper for new board and new containers. At high recycle rates, the strength properties of corrugated containers (produced from recycled OCC) can ultimately deteriorate to unacceptable levels.
It would be desirable to provide a process to convert OCC to nanocellulose. The nanocellulose would have many uses, one of which could be to improve strength of new corrugated containers containing recycled OCC.